The territory was upgraded to the status of an autonomous republic within the Ukrainian SSR following a referendum that was held on 20 January 1991. Later in 1991, when the Soviet Union collapsed, Crimea remained part of the newly independent Ukraine.

On 14 October 1993, the Crimean parliament established the post of President of Crimea and agreed on a quota of Crimean Tatars represented in the Council of 14. However, on 17 March 1995, the parliament of Ukraine abolished the Crimean Constitution of 1992, all the laws and decrees contradicting those of Kiev – including laws that guaranteed representation for the Crimean Tartars and other ethnic groups – and removed Yuriy Meshkov (the President of Crimea) as well as the office of The President of Crimea.[19][20] After an interim constitution, the Constitution of the Autonomous Republic of Crimea was put into effect, changing the territory's name to the Autonomous Republic of Crimea.

Following the 2014 Ukrainian revolution that ousted the pro-Russian Ukrainian President Viktor Yanukovych on 22 February 2014, there was a push by pro-Russian protesters for Crimea to secede from Ukraine and seek assistance from Russia.[27] Crimea had largely voted for Viktor Yanukovych during the presidential elections of 2004 and 2010 and his Party of Regions also won most of the votes from Crimea in the Ukrainian parliamentary elections of 2006, 2007 and 2012, and in the Crimean parliamentary elections of 2006 and 2010.[28]

On 26 February 2014, thousands of pro-Russian and pro-Ukraine protesters clashed in front of the parliament building in Simferopol. Two days later, Russian forces occupied airports and other strategic locations in Crimea[29] which the interim Government of Ukraine described as an invasion and occupation.[30][31] Gunmen, either armed militants or Russian special forces, occupied the Crimean parliament. Under armed guard and with the doors locked, members of parliament reportedly elected Sergey Aksyonov as the new Crimean Prime Minister.[32] The de facto Crimean Prime Minister Sergey Aksyonov said that he asserted sole control over Crimea's security forces and appealed to Russia "for assistance in guaranteeing peace and calmness" on the peninsula. The central Ukrainian government did not recognize the Aksyonov administration and considers it illegal.[33][34] Ousted Ukrainian President Viktor Yanukovich sent a letter to Putin asking him to use military force in Ukraine to restore law and order.[35] The Russian foreign ministry stated that "movement of the Black Sea Fleet armored vehicles in Crimea (...) happens in full accordance with basic Russian-Ukrainian agreements on the Black Sea Fleet".[36]

On 1 March, the Russian parliament granted President Vladimir Putin the authority to use military force in Ukraine.[37] On 4 March several Ukrainian bases and navy ships in Crimea reported being intimidated by Russian forces and Ukrainian warships were also effectively blockaded in Sevastopol.[38][39]

On 6 March, members of the Crimean Parliament asked the Russian government for the region to become a subject of the Russian Federation with a referendum on the issue set for the Crimean region for 16 March. The Ukrainian government, the European Union, and the US all challenged the legitimacy of the request and of the following referendum. Article 73 of the Constitution of Ukraine states: "Alterations to the territory of Ukraine shall be resolved exclusively by an All-Ukrainian referendum."[40] International monitors arrived in Ukraine to assess the situation in Crimea but were halted by armed militants at the Crimean border.[41][42]

The day before the referendum, Ukraine's national parliament voted to dissolve the Supreme Council of Crimea as its leaders were finalising preparations for the vote.[45]

The 16 March referendum required voters to indicate a positive choice between "Do you support rejoining Crimea with Russia as a subject of the Russian Federation?" and "Do you support restoration of the 1992 Constitution of the Autonomous Republic of Crimea and Crimea's status as a part of Ukraine?" There was no option on the ballot to maintain the status quo and although some Ukrainian outlets considered the questions to be equivalent to "join Russia immediately" or "declare independence and then join Russia"[46][47] support for the second question would have restored the Republic's autonomous status within Ukraine.[19][48] The official turnout for the referendum was 83%, and the overwhelming majority of those who voted (95.5%)[49] supported the option of rejoining Russia. However, a BBC reporter claimed that a "huge number of people in the minority population – the Tatars and Ukrainians – abstained from the vote", making it difficult to tell if the figures added up.[50]

Following the referendum, the members of the Supreme Council voted to rename themselves the State Council of the Republic of Crimea and also formally appealed to Russia to accept Crimea as part of the Russian Federation.[51]

There were 25 administrative areas in the Autonomous Republic of Crimea: 14 raions (districts) and 11 mis'kradas and mistos (city municipalities), officially known as territories governed by city councils.[58]

^Marxen, Christian (2014). "The Crimea Crisis – An International Law Perspective"(PDF). Zeitschrift für ausländisches öffentliches Recht und Völkerrecht (Heidelberg Journal of International Law). 74. Organizing and holding the referendum on Crimea's accession to Russia was illegal under the Ukrainian constitution. Article 2 of the constitution establishes that "Ukraine shall be a unitary state" and that the "territory of Ukraine within its present border is indivisible and inviolable". This is confirmed in regard to Crimea by Chapter X of the constitution, which provides for the autonomous status of Crimea. Article 134 sets forth that Crimea is an "inseparable constituent part of Ukraine". The autonomous status provides Crimea with a certain set of authorities and allows, inter alia, to hold referendums. These rights are, however, limited to local matters. The constitution makes clear that alterations to the territory of Ukraine require an all-Ukrainian referendum.

^Higgons, Andrew, Grab for Power in Crimea Raises Secession Threat, New York Times, 28 February 2014, page A1; reporting was contributed by David M. Herszenhorn and Andrew E. Kramer from Kiev, Ukraine; Andrew Roth from Moscow; Alan Cowell from London; and Michael R. Gordon from Washington; with a graphic presentation of linguistic divisions of Ukraine and Crimea

^Shuster, Simon (10 March 2014). "Putin's Man in Crimea Is Ukraine's Worst Nightmare". Time. Retrieved 8 March 2015. Before dawn on Feb. 27, at least two dozen heavily armed men stormed the Crimean parliament building and the nearby headquarters of the regional government, bringing with them a cache of assault rifles and rocket propelled grenades. A few hours later, Aksyonov walked into the parliament and, after a brief round of talks with the gunmen, began to gather a quorum of the chamber's lawmakers.